OC, next time something like that happens try this first, ok?
bootup and press F8 before windows loads...
select safe mode...
Boot into Safe mode and then uninstall what you installed, if it will not let you...
run regedit and do a search for Pixtudio, and or in this instance Abracadabra...
then delete the regitry entries that deal with the offending program... But do not delete the registry entery pointing to the save compressed file ( abracadabra.zip, dxtheme, etc)
then reboot and it should fix the problem without doing th go back and loosing everything that was done after the restore point in Go Back....
also, you might attempt to reboot into " the last known good configuration"
boot up press F8 before windows loads and select the "boot up last known good configuration" wording might be a bit different but it will be obvious which one I mean...
worth a try to avoid bad things...